<template>
  <div class="spec-preview">
    <img :src="skuImage" />
    <div class="event" @mousemove="zoomImg($event)" ref="event"></div>
    <div class="big" >
      <img :src="skuImage" ref="big"/>
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuImageList"],
  data() {
    return {
      skuImage: this.skuImageList[0]?.imgUrl,
    };
  },
  mounted() {
    this.$bus.$on("clickSlide", (index) => {
      this.skuImage = this.skuImageList[index].imgUrl;
    });
  },
  methods: {
    zoomImg(e) {
      const mask = this.$refs.mask;
      const event = this.$refs.event;
      const big = this.$refs.big;

      //mask的定位距离 鼠标在父级定位盒子内的坐标-mask的一半 让其居中
      let left = e.offsetX - mask.offsetWidth / 2;
      let top = e.offsetY - mask.offsetHeight / 2;

      // 限制位置
      const littleMaxW = event.offsetWidth - mask.offsetWidth;
      const littleMaxH = event.offsetHeight - mask.offsetHeight;
      if (left < 0) left = 0;
      if (left > littleMaxW) left = littleMaxW;
      if (top < 0) top = 0;
      if (top > littleMaxH) top = littleMaxH;

      mask.style.left = left + "px";
      mask.style.top = top + "px";
      //大图移动
      // 小图与大图之间比例：小图：大图宽度比例  小图：大图高度比例 是2倍关系
      big.style.left=-2*left+'px'
      big.style.top=-2*top+'px'

    },
  },
  computed: {},
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;
  cursor: move;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.2);
    position: absolute;
    left: 100px;
    top: 100px;
    display: none;
  
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>